Effects of MIG welding Current in Brazing Process on Mechanical Properties and Microstructure of Galvanized Steel Brazing Seam
Titiwat Wattanasrisin ¹ Trinet Yingsamphancharoen ² and Aphichart Rodchanarowan ^1*
1 Department of Materials Engineering, Faculty of Engineering, Kasetsart University, 50 Ngamwongwan Rd., Lat Yao, Chatuchak, Bangkok, 10900, Thailand.
² Department of Welding Engineering Technology, College of Industrial Technology, King Mongkut’s University of Technology North Bangkok, 1518 Pracharat 1 Road, Wongsawang, Bangsue, Bangkok 10800.

Abstract

In this study, the effects of welding currents (ranged from 70, 75, 80, 85, 90 and 95 Amp) on mechanical properties and microstructure of brazing seam from galvanized steel with Copper-Silicon filler by MIG brazing process were reported. It was found that higher welding currents increased the ability of filler penetration into the gap. According to the Microstructures of brazing seam using scanning electron microscopy (SEM), there was precipitation of intermetallic phase (Fe5Si3(Cu)) distributed all over the matrix; while enlargement of Fe5Si3(Cu) was detected at higher welding currents. The presence of the Fe5Si3(Cu) in the brazing seam resulted in an increase in hardness. The strength of brazing seam from every welding current was higher than as-received galvanized steel coupon.